The present invention relates to a hopper for use in an automatic weighing apparatus, and more particularly to a mechanism for opening and closing a hopper gate and a support device for such a hopper.
A conventional automatic combinatorial weighing apparatus has a plurality of weighing machines arranged in a circular pattern and finds weights of batches of articles supplied to the weighing machine. Articles of a certain desired total weight can be obtained by selecting a combination of determined weights which is optimum for the desired total weight and discharging those articles contained in the selected weighing machines. Each of the weighing machines is equipped with a weighing hopper for containing a batch of articles therein and a pool hopper disposed upwardly of the weighing hopper for quickly supplying a next batch of articles to be weighed into the weighing hopper when the previously weighed batch of articles has been discharged from the weighing hopper.
The weighing hopper has a gate for opening and closing its article discharge port and a link mechanism actuatable under the control of an external source for opening and closing the gate. The weighing apparatus also has an attachment mechanism for attaching each weighing hopper to the companion weighing machine. Conventional hoppers are disadvantageous in that they are quite complex in structure, highly costly to construct, and heavy.
The above automatic weighing apparatus is normally used in combination with a packaging apparatus which is supplied with articles discharged through a collection chute from the weighing hoppers of the selected weighing machines. To increase the article handling capability, the automatic weighing apparatus is controlled to enable the weighing hoppers to discharge the weighed articles into the collection chute and also to enable the pool hoppers to charge next batches of articles into the weighing hoppers substantially at the same time making any loss of time as small as possible. Alternatively, each of the weighing hoppers is provided with two gates, and the collection chute is of a double construction composed of an outer chute for receiving articles discharged from one of the gates of the weighing hopper and an inner chute for receiving articles discharged from the other gate thereof. The two gates of each weighing hopper are alternately opened and closed to discharge the articles alternately into the inner and outer collection chutes, thereby shortening the time interval in which the articles are supplied from the weighing apparatus into the packaging apparatus.
The two gates on each weighing hopper are coupled with respective link mechanisms for opening and closing the gates, the prior link mechanisms being mounted independently on opposite outer side surfaces of a hopper body. This arrangement has resulted in an increased hopper width or an increased amount of space being taken up by each hopper. The hoppers are therefore arranged at wide pitches, with the consequence that the automatic weighing apparatus with the circularly arranged weighing machines is large in overall size, or the number of weighing machines installed is limited, a limitation which has been an obstacle to efforts to improve the weighing accuracy.
With the automatic combinatorial weighing apparatus of the type described above, the pool hoppers are removably attached to the weighing machines or removably installed in other attachment positions for cleaning purpose.
FIGS. 1 through 3 of the accompanying drawings show a general conventional hopper attachment construction by way of example. An attachment plate B is fixed to a mount structure A such as a weighing machine, and a pair of guide members D, D having an L-shaped cross section are mounted on a hopper C. The hopper C is installed on the mount structure A by inserting the attachment plate B between the guide members D, D. With this construction, it is tedious and time-consuming to manufacture the components since the back surfaces of the attachment plate B and the hopper C held in contact therewith and the inner surfaces of the guide members D, D should be finished so as to have the required shape and flatness. Any gap or backlash between the attachment plate and the guide members causes the hopper to vibrate or wobble due to vibrations of the apparatus and shocks imposed when the gate is opened and closed. Vibrations or wobbling movements of the weighing hoppers attached to the weighing machines adversely affect the weighing machine and result in a reduced degree of weighing accuracy.